Is my battery on its way out?

[zmaster007]

As above - my symptoms are:
- Reverse lights get brighter when I rev
- Longer starts from cold than I would expect
- 12.4v voltage across the battery when the car is off
- 14.0v across the battery when the car is idling
- Revs dip at idle when I'm coming to a stop and dipped the clutch

If so, do I need an AGM battery? If not - alternator?

Any advice is greatly appreciated

 

[BigT]

It sounds like the battery to me - they're the symptoms I've had on a few cars when its on its way out. Look at the old battery to determine if you need an AGM battery for sure. I think as standard it should have one and I know I fitted a Bosch S6 AGM battery to mine a couple of years ago and it has stood the test of time as the car can often not be in use for weeks at a time and it starts on the button.

I'm sure someone will be along with a more scientific test for ruling out your alternator first though before you spend big bucks on a battery.